This invention relates to articles, particularly brass articles, having a multi-layered decorative and protective coating having the appearance or color of nickel thereon.
It is currently the practice with various brass articles such as faucets, faucet escutcheons, door knobs, door handles, door escutcheons and the like to first buff and polish the surface of the article to a high gloss and to then apply a protective organic coating, such as one comprised of acrylics, urethanes, epoxies and the like, onto this polished surface. This system has the drawback that the buffing and polishing operation, particularly if the article is of a complex shape, is labor intensive. Also, the known organic coatings are not always as durable as desired, and are susceptible to attack by acids. It would, therefore, be quite advantageous if brass articles, or indeed other articles, either plastic, ceramic, or metallic, could be provided with a coating which provided the article with a decorative appearance as well as providing wear resistance, abrasion resistance and corrosion resistance. It is known in the art that a multi-layered coating can be applied to an article which provides a decorative appearance as well as providing wear resistance, abrasion resistance and corrosion resistance. This multi-layer coating includes a decorative and protective color layer of a refractory metal nitride such as a zirconium nitride or a titanium nitride. This color layer, when it is zirconium nitride, provides a brass color, and when it is titanium nitride provides a gold color.
U.S. Pat. Nos. 5,922,478; 6,033,790 and 5,654,108, inter alia, describe a coating which provides an article with a decorative color, such as polished brass, provides wear resistance, abrasion resistance and corrosion resistance. It would be very advantageous if a coating could be provided which provided substantially the same properties as the coatings containing zirconium nitride or titanium nitride but instead of being brass colored or gold colored was nickel colored. The present invention provides such a coating.
The present invention is directed to an article such as a plastic, ceramic or metallic article having a decorative and protective multi-layer coating deposited on at least a portion of its surface. More particularly, it is directed to an article or substrate, particularly a metallic article such as stainless steel, aluminum, brass or zinc, having deposited on its surface multiple superposed layers of certain specific types of materials. The coating is decorative and also provides corrosion resistance, wear resistance and abrasion resistance. The coating provides the appearance of nickel, i.e. has a nickel color tone. Thus, an article surface having the coating thereon simulates a nickel surface.
The article first has deposited on its surface a polymeric basecoat layer. On top of the polymeric layer is then deposited, by vapor deposition such as physical vapor deposition, one or more vapor deposited layers. More particularly disposed over the polymeric basecoat layer is a protective color layer comprised of a refractory metal nitride or a refractory metal alloy nitride wherein the refractory metal nitride or refractory metal alloy nitride is lightly nitrided, that is to say contains a small amount, i.e. less than stoichiometric amount, of nitrogen. Generally this amount of nitrogen is between about 6 to about 45 atomic percent.
FIG. 1 is a cross sectional view of a portion of the substrate having a multi-layer coating comprising a polymeric base coat and a refractory metal nitride color and protective layer directly on the top polymeric layer;
FIG. 2 is a view similar to FIG. 1 except that a refractory metal strike layer is present intermediate the polymeric layer and the refractory metal nitride layer; and
FIG. 3 is a view similar to FIG. 2 except that a refractory metal oxide layer is present on the refractory metal nitride color layer.